Fin-based field effect transistors (FINFETs) are vertical transistor devices in which a semiconductor fin is located on a substrate and is used to define the source, drain, and channel regions of the device. The gate structure overlies the fin in the channel area, and in some configurations multiple fins may be used to provide a multi-gate transistor architecture. The multiple gates may be controlled by a single gate electrode, where the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes.
One example FINFET device is set forth in U.S. Pat. No. 8,310,013 to Lin et al., which is hereby incorporated herein in its entirety by reference. The FINFET device includes a substrate of a crystalline semiconductor material having a top surface of a first crystal plane orientation, a fin structure of the crystalline semiconductor material overlying the substrate, a gate structure over a portion of the fin structure, and an epitaxial layer over another portion of the fin structure. The epitaxial layer has a surface with a second crystal plane orientation. The epitaxial layer and underlying fin structure include a source and drain region. The source region is separated from the drain region by the gate structure. A. channel is defined in the fin structure from the source region to the drain region, and aligned in a direction parallel to both the surface of the epitaxial layer and the top surface of the substrate.
Despite the existence of such configurations, further enhancements in such devices may be desirable in some applications, particularly next generation devices with relatively small dimensions.